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Related papers: Performance of the coupled cluster singles and dou…

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We propose a non-iterative, post hoc correction to the unitary coupled cluster theory with single, double, and triple excitations (UCCSDT) ansatz, which considers the leading-order effects of neglected quadruple excitations. We present two…

Chemical Physics · Physics 2025-08-14 Zachary W. Windom , Luke Bertels , Daniel Claudino , Rodney J. Bartlett

The dual exponential coupled cluster (CC) theory proposed by Tribedi et al.[J. Chem. Theory Comput. 2020, 16, 10, 6317-6328] performs significantly better than the coupled cluster theory with singles and doubles excitations (CCSD) due to…

Computational Physics · Physics 2023-07-26 Anish Chakraborty , Rahul Maitra

Coupled-cluster theory with single, double, and perturbative triple excitations (CCSD(T)) -- often considered the "gold standard" of main-group quantum chemistry -- is inapplicable to three-dimensional metals due to an infrared divergence,…

Materials Science · Physics 2023-03-21 Verena A. Neufeld , Timothy C. Berkelbach

Simulating molecules using the Variational Quantum Eigensolver method is one of the promising applications for NISQ-era quantum computers. Designing an efficient ansatz to represent the electronic wave function is crucial in such…

Chemical Physics · Physics 2022-05-09 Dmitry A. Fedorov , Yuri Alexeev , Stephen K. Gray , Matthew Otten

A major difficulty in quantum simulation is the adequate treatment of a large collection of entangled particles, synonymous with electron correlation in electronic structure theory, with coupled cluster (CC) theory being the leading…

Chemical Physics · Physics 2024-06-06 Zachary W. Windom , Daniel Claudino , Rodney J. Bartlett

Coupled-cluster theory with single and double excitations (CCSD) is a promising ab initio method for the electronic structure of three-dimensional metals, for which second-order perturbation theory (MP2) diverges in the thermodynamic limit.…

Materials Science · Physics 2021-06-16 James M. Callahan , Malte F. Lange , Timothy C. Berkelbach

Unitary cluster expansions of the electronic wavefunction have recently gained much interest because of their use in conjunction with quantum algorithms. In this contribution, we investigate some aspects of an ansatz using generalized…

Chemical Physics · Physics 2022-10-12 Andreas Köhn , Jeppe Olsen

In this paper, we present a parallel computing method for the coupled-cluster singles and doubles (CCSD) in periodic systems. The CCSD in periodic systems solves simultaneous equations for single-excitation and double-excitation amplitudes.…

Strongly Correlated Electrons · Physics 2019-11-04 Takumi Yamashita , Taichi Kosugi , Yu-ichiro Matsushita , Tetsuya Sakurai

The accuracy at which total energies of open-shell atoms and organic radicals may be calculated is assessed for selected coupled cluster perturbative triples expansions, all of which augment the coupled cluster singles and doubles (CCSD)…

Chemical Physics · Physics 2016-05-17 Janus Juul Eriksen , Devin A. Matthews , Poul Jørgensen , Jürgen Gauss

A novel approach to rapidly converging high-level coupled-cluster (CC) energetics in an automated fashion is proposed. The key idea is an adaptive selection of the excitation manifolds defining higher-than-two-body components of the cluster…

Chemical Physics · Physics 2023-08-25 Karthik Gururangan , Piotr Piecuch

A novel implementation of the coupled-cluster singles and doubles (CCSD) approach is presented that is specifically tailored for the treatment of large, symmetric systems. It fully exploits Abelian point-group symmetry and the use of the…

Chemical Physics · Physics 2023-12-07 Tommaso Nottoli , Jürgen Gauss , Filippo Lipparini

We introduce a range-separation approximation to coupled cluster doubles (CCD) theory that successfully overcomes limitations of regular CCD when applied to the uniform electron gas. We combine the short-range ladder channel with the…

Chemical Physics · Physics 2014-05-07 James J. Shepherd , Thomas M. Henderson , Gustavo E. Scuseria

We demonstrate the accuracy of ground-state energies of the transcorrelated Hamiltonian, employing sophisticated Jastrow factors obtained from variational Monte Carlo, together with the coupled cluster and distinguishable cluster methods at…

We recently proposed a novel approach to converging electronic energies equivalent to high-level coupled-cluster (CC) computations by combining the deterministic CC($P$;$Q$) formalism with the stochastic configuration interaction (CI) and…

Chemical Physics · Physics 2021-03-23 J. Emiliano Deustua , Jun Shen , Piotr Piecuch

Recent disagreement between state-of-the-art quantum chemical methods, coupled cluster with single, double and perturbative triples excitations and fixed-node diffusion Monte Carlo, calls for systematic examination of possible sources of…

Chemical Physics · Physics 2025-05-14 S. Lambie , C. Rickert , D. Usvyat , A. Alavi , D. Kats

The (T) and [T] perturbative corrections are derived for multicomponent coupled-cluster theory with single and double excitations (CCSD). Benchmarking shows that multicomponent CCSD methods that include the perturbative corrections are more…

Chemical Physics · Physics 2022-07-01 Dylan Fowler , Kurt R. Brorsen

Quantum embedding methods have recently developed significantly to model large molecular structures. This work proposes a novel wave function theory in density functional theory (WTF-in-DFT) embedding scheme based on pair-coupled cluster…

Chemical Physics · Physics 2024-01-10 Rahul Chakraborty , Katharina Boguslawski , Paweł Tecmer

Unitary coupled cluster (UCC), originally developed as a variational alternative to the popular traditional coupled cluster method, has seen a resurgence as a functional form for use on quantum computers. However, the number of excitors…

Chemical Physics · Physics 2021-01-07 Maria-Andreea Filip , Alex J. W. Thom

Numerous numerical studies have shown that geminal-based methods are a promising direction to model strongly correlated systems with low computational costs. Several strategies have been introduced to capture the missing dynamical…

Chemical Physics · Physics 2023-03-22 Artur Nowak , Katharina Boguslawski

A number of iterative and perturbative approximations to the full equation-of-motion coupled cluster method with single, double, and triple excitations (EOM-CCSDT) are evaluated in the context of calculating the K-edge core-excitation and…

Chemical Physics · Physics 2025-03-26 Devin A. Matthews